ABSTRACT
OBJECTIVE: The objective of this study was to evaluate the adequacy of the user seal check (USC) in predicting N95 respirator fit. DESIGN: This was a prospective, observational study conducted from May to September 2020. SETTING: The study setting included three private intensive care units (ICUs) in Victoria, Australia. PARTICIPANTS: ICU staff members in three private ICUs in Melbourne and regional Victoria participated in this study. MAIN OUTCOME MEASURES: The main outcome measure is the proportion of participants who passed a USC and subsequently failed fit testing of an N95 respirator. INTERVENTION: Three different respirators were available: two N95 respirator brands and CleanSpace HALO® powered air-purifying respirator. Participants were sequentially tested on N95 respirators followed by powered air-purifying respirators until either successful fit testing or failure of all three respirators. The first N95 tested was based on the availability on the day of testing. The primary outcome was failure rate of fit testing on the first N95 respirator type passing a USC. RESULTS: Of 189 participants, 22 failed USC on both respirators, leaving 167 available for the primary outcome. Fifty-one of 167 (30.5%, 95% confidence interval = 23.7-38.1) failed fit testing on the first respirator type used that had passed a USC. CONCLUSION: USC alone was inadequate in assessing N95 respirator fit and failed to detect inadequate fit in 30% of participants. Mandatory fit testing is essential to ensure adequate respiratory protection against COVID-19 and other airborne pathogens. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry: ACTRN12620001193965.